Joris DeeneYes, a company can have a B2B contract voided for mistake if it was misled by incomplete or inaccurate information when it was formed. Indeed, even in business relationships there are strict information duties, especially when one party is a technical specialist and the other is a layman in that particular field. If the professional service provider violates this duty of information and conceals crucial matters about cost or technical feasibility or presents them in a rosier light, the aggrieved company can successfully challenge the contract.
The facts and legal context
A company specializing in electronic bicycles entered into a business technology contract with an IT service provider to modernize and integrate its online sales channels. Specifically, the idea was to merge an existing Belgian and Dutch web store via a proposed middleware solution. After extensive pre-contractual discussions, a detailed quotation was prepared with a technical description and preliminary project schedule, after which the project was started.
However, during the execution of the works, the software provided by the IT supplier was found to have serious shortcomings: the application was incomplete, error-prone and technically inadequate. This led to necessary additional work not anticipated in the bid, resulting in significant additional costs. In addition, the agreed deadlines were systematically exceeded, causing significant delays to the project.
The bicycle dealer subsequently decided to unilaterally and extrajudicially terminate the contract for persistent failure to meet deadlines. In court, she sought the annulment of the contract on the basis of the defects of consent fraud and mistake, citing incorrect information about the service provider's technical expertise. In doing so, she referred to the rules on transparency obligations and the prohibition of unfair and misleading market practices between companies in the Code of Economic Law (CEL).
The court's decision
In a ruling dated April 28, 2025, the Antwerp Court of Appeal ruled that the agreement between the parties was effectively void.
First, the court ruled that fraud was not proven because the client could not provide evidence of an intentional misrepresentation of facts or malicious intent by the IT service provider.
However, the court did find that the duty of transparency had been violated and that there had been a misleading trade practice, which led to the consent defect mistake. Because the defective and misleading information was a decisive element in the formation of the contract, the nullity of the contract could be invoked. As a sanction, the court voided the contract and ordered the IT service provider to refund all amounts paid and credit the invoices issued.
Legal analysis and interpretation
This ruling illustrates an important convergence between market practice law from the CEL and general contract law from the Civil Code. In B2B relationships, jurisprudence generally assumes a higher level of knowledge and experience, so the threshold for assuming a defect of consent (such as mistake) is in principle higher than for consumers.
Here, however, the court of appeal emphasized that the provisions of the CEL (in particular Articles III.77, VI.104 and VI.105 CEL), which require companies to provide all essential information clearly and in a timely manner, feed directly into the assessment of the validity of the consent. A breach of the pre-contractual information duty may therefore also constitute a consent defect (mistake).
Mistake normally requires that the error be excusable; even a prudent and reasonable person in the same circumstances would have erred. This excusability requirement implies some duty of inquiry for the erring party. The court nuanced this duty by stating that although this was a B2B relationship, the purchasing company was acting outside its own core expertise (bicycle sales versus IT development). This placed a special duty of disclosure on the technically specialized contracting party. Because the IT supplier concealed crucial information about technical feasibility and painted an overly positive picture of its own expertise, the client's error was legitimate and excusable. Moreover, the court assumed that the purchaser had also excusably erred about the total project cost price, since misrepresentation of price is not a misunderstanding beyond normal expectations.
What this specifically means
- For service providers and experts: You bear a heavy responsibility in the pre-contractual phase. If you incompletely inform a B2B customer about the real capabilities of your software, services or the expected total cost, you are taking a big risk. Withholding essential technical hurdles can lead to the complete annulation of the contract, with you having to repay fees already received in full.
- For declining SMEs: You are not outlawed in the B2B context. If, as a ‘layman,’ you rely on a highly specialized partner (such as an IT company, marketing agency or technical engineering firm), you may reasonably trust their expertise. If it turns out afterwards that the service provider presented things far too rosy and misled you about essential elements, the contract can be voided for mistake.
Frequently Asked Questions
What is the difference between fraud and mistake?
Fraud always requires an external, intentional factor: the co-contractor must have intentionally or maliciously caused the deception through artifice or deceptive acts. In the case of mistake (in the narrow sense), this requirement of intentional deception is absent; it is sufficient that there was a misrepresentation that was decisive in concluding the contract and is ‘excusable.
Is a mistake about price enough to nullify a contract?
In principle, error that is solely about the price is legally excluded. However, if the misconception about the price is the direct result of a deception about the nature, extent or essential characteristics of the subject matter of the contract, it may well qualify as a voidable mistake.
Conclusion
The ruling clearly shows that the prohibition of misleading market practices and the pre-contractual information duty are powerful instruments in Belgium, including between companies. Misleading about essential elements by an expert can lead to excusable mistake and the subsequent nullity of the contract.
Dutch 
English